def add_one_by_one():
    sum = 0
    for i in range(0, 100):
        sum = sum + i

def add_one_by_one2():
    n=100
    sum=(1+n)*n/2

def add_one_by_one3(arr,n):
    sum=0
    n=100
    for i in range(0,100):
        for j in range(0,100):
            sum=sum+arr[i][j]

